Cycles render stopped rendering
The frame renders just fine, it just takes a very, very, very long time to synchronize the objects... You are using a highly subdivided model. In my opinion you don't need that many vertices.

Try simplifying the topology and reduce the number of vertices as much as you can. 



Additionally, instead of animating the visibility of the objects, play with shapekeys, so that you are dealing with a constant number of vertices for the start and end of the morph transformation.